The invention concerns an electrode arrangement comprising a first electrode cable which is to be inserted into the coronary sinus and which has an electrode conductor and at least one electrode for outputting and/or receiving electrical signals in the coronary sinus.
Heart stimulation by way of the coronary sinus (CS) is nowadays a form of therapy which is used only rarely. The cause of this, besides difficulties in positioning the electrodes and the threat of complications such as perforation, is also the lack of suitable electrode arrangements.
However, situations are known in which CS-stimulation represents a preferred form of therapy, for example in regard to the implantation of anti-tachycardial pacemakers, in which the stimulation electrode is to be in the proximity of the re-entry circuit. Stimulation of the left-hand half of the heart by way of the CS and a cardiac vein is also conceivable.
Therefore the object of the invention is to provide an electrode arrangement for electrical cardiac therapy.
That object is attained by an electrode arrangement having the features of claim 1.
In accordance with the invention, longitudinally slidably guidable in the lumen of the first electrode cable at least in a longitudinal portion-wise manner is a second electrode cable which can issue from the first electrode cable through an opening at the distal end thereof and which is adapted for insertion into a cardiac vein which opens into the coronary sinus.
The electrode arrangement according to the invention is designed primarily for stimulation of the left-hand half of the heart by way of the coronary sinus (CS) and a left-hand cardiac vein. The design configuration thereof permits relatively easy insertion of the electrodes into the vessels. Only one vessel incision is required for the insertion of both electrode cables, for example in the Vena cephalica or the Vena subclavia or other vessels. In that respect, firstly the first electrode cable can be inserted and placed in the coronary sinus. Then, the second electrode cable can be passed through the lumen of the first electrode cable and, issuing from the distal end thereof, inserted into a cardiac vein.
After the step of positioning the first electrode cable its lumen can alternatively firstly be used for inserting a Swan-Ganz catheter in order to inject an X-ray contrast agent into the cardiac veins. In that way the cardiac veins can then be rendered visible by means of fluoroscopy. That procedure facilitates the subsequently necessary operation of precisely positioning the second electrode cable in the cardiac vein.
Alternatively however the second electrode cable can also already be introduced, upon insertion of the first electrode cable, as far as the distal opening thereof.
The electrode of the first electrode cable is preferably in the form of a ring electrode. In a preferred embodiment of the invention, the first electrode cable has two axially spaced ring electrodes which can be positioned in the CS. They are preferably insulated relative to each other and can be polarized in opposite relationship.
Fixing of the first electrode cable in the coronary sinus can be effected both actively and also passively, in which respect care is to be taken to ensure that the anchoring device involves an only minimal congestion or flow-stemming effect. For example an anchoring device can be in the form of a helical screwthread portion comprising a flexible plastic material and can be arranged on the outer sheathing of the first electrode cable in the region of its distal end. Fixing is also conceivable by means of fins of elastic plastic material, which are of a dimension corresponding to the CS and which are inclined towards the proximal end. In order to reduce the flow resistance of such a fixing device the fins may each extend only over a portion of the periphery of the sheathing and can be arranged in displaced relationship both in the axial and in the peripheral direction.
In a development of the invention the first electrode cable has an external sheathing with a receiving opening for the second electrode cable. Between the receiving opening and the distal electrode the lumen of the first electrode cable is increased to such an extent that the second electrode cable can be passed along the electrode conductor of the first electrode cable.
In a further embodiment arresting of the axial position of the second electrode cable relative to the external sheathing is possible. In that way, after the electrodes have been positioned in the CS and in the cardiac vein, the spacing of the cardiac vein electrode with respect to the CS-electrode or electrodes is prevented from altering.
The arresting action is preferably achieved by means of a clamping device at the receiving opening, for example with an eccentric screw which extends in the lumen of the external sheathing perpendicularly to the longitudinal axis between the first and second electrode lines.
For that purpose the cross-sectional profile of the external sheathing is widened at the receiving opening. At the same time that makes it easier to introduce the second electrode cable.
A seal at the distal opening of the first electrode cable prevents fluid from passing into the lumen of the external sheathing. The lumen is preferably also sealed off as long as the second electrode cable has not yet been inserted into the cardiac vein.
In a further embodiment the second electrode cable tapers towards its distal end in order to form a low level of flow resistance.
Preferably a tip electrode at the distal end of the second electrode cable is used for stimulation of the left ventricle. However, it is in principle also possible to use electrode arrangements with one or more ring electrodes in the portion of the second electrode cable, which projects in a distal direction out of the external sheathing of the first electrode cable.
A further embodiment provides a device for fixing the second electrode cable in the cardiac vein. With suitable dimensioning, it can be of a similar configuration to the fixing device for the CS.
An extension with at least one marker can be arranged at the distal end of the second electrode cable. The marker can be located by means of an imaging process from outside the body. For example, the marker includes a material or is made completely from a material with which a contrast in relation to body-specific materials can be produced in an image produced by the imaging process. The marker for example may contain gold for X-ray irradiation of the patient for monitoring the procedure for inserting the electrodes. One or more such markers may also be provided in the distal end region of the first electrode cable.
The extension is made from flexible material and in particular can be adapted to be controllable, for example insofar as the guide wire for the second electrode cable can be introduced thereinto. It is however also possible to conceive of a design configuration in which the extension is substantially J-shaped or horn-shaped and upon being advanced in the vessels is guided by rotation of the second electrode cable.
To achieve a high level of breaking strength the electrode conductor of the first electrode cable is of a two-coil configuration. In an embodiment with two CS-electrodes, two respectively electrically insulated wires extend in each of the two coils of the electrode conductor.
In a further embodiment, a respective guide wire can be introduced into the lumen of the first and the second electrode conductors, for insertion and positioning of the electrode cable.
In order to provide sufficient clearance in regard to positioning of the second electrode cable and in regard to establishing the spacing between the cardiac vein electrode and the CS-electrodes, the second electrode cable can extend in the form of an annular loop, between its proximal end and the entry into the receiving opening of the first electrode cable.